Because you must take in fewer calories than you burn to lose weight, you may assume that fasting would be the most effective method to reach your goal. However, depriving your body of too many calories can be risky, and the weight loss results you do see are unlikely to be permanent.
Potential Weight Loss
Eating few to no calories may cause you to lose weight quickly, but you will also likely regain the weight just as quickly as you lost it. Also, dropping too many calories at once doesn't lead to large amounts of fat loss because the body simply can't lose fat that quickly. Weight loss from dramatic diets and fasts also comes from loss of muscle mass and water weight, according to MayoClinic.com.
Risks
Ignoring hunger pangs can be dangerous because you are denying your body the energy and nutrients it needs to function. This can lead to unpleasant symptoms such as headaches, abdominal discomfort, fatigue, lightheadedness, mood swings and fainting. Fasting can also be risky if you're trying to lose weight because it can slow down your metabolism, and it increases your risk of binging on calories in the evening due to feelings of deprivation, warns Health Services at Columbia University. Although you reduce your risk of low blood sugar and dehydration if you fast infrequently and continue to drink water and 100 percent fruit juice during fasts, you will still be better off consulting your doctor to rule out the possibility of further health complications.
Recommended Weight Loss
Most physicians warn against losing more than about 1 to 2 lbs. each week. By losing more than 2 lbs. a week, you risk losing muscle and water weight as opposed to weight from excess fat. Staying within the safe range will also improve your chances of maintaining weight loss and reduce your risk of side effects from nutritional deficiencies. To stay within the safe range of 1 to 2 lbs. per week, you would have to create a deprivation of about 500 to 1,000 calories each day because 1 lb. of fat is about 3,500 calories, according to MayoClinic.com.
Considerations
Although going on a dramatic fast isn't necessarily the most effective way to lose weight, research published in the "American Journal of Clinical Nutrition" in 2009 suggests that going on a short-term modified fast may be helpful. Participants in the study --- who consumed about 25 percent of their energy needs on alternating days rather than skipping calories altogether --- lost nearly six percent of their baseline weight after eight weeks of treatment. They also saw decreases in risk factors for cardiovascular disease risks, including high cholesterol and blood pressure levels. Still, more research would need to be conducted to ascertain the long-term efficacy of this diet plan.
References
- Health Services at Columbia University: Fast All Day and Feast at Night --- Healthy?
- "American Journal of Clinical Nutrition"; Short-term Modified Alternate-day Fasting: A Novel Dietary Strategy for Weight Loss and Cardioprotection in Obese Adults; K. Varady, et al.; 2009
- Beth Israel Deaconess Medical Center; Detox Diets Debunked; Maria Adams, MS, MPH, RD; January 2009
- "Health"; Is Fasting Dangerous?; Julie Upton, MS, RD; October 2010
- "Today" Health; Fasting: Does It Really Work?; Madelyn Fernstrom, Ph.D., CNS; December 2006
- ScienceDaily; Alternate-day Fasting: How Good Is it for Your Health?; September 2007
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